Lameness of the Horse / Veterinary Practitioners' Series, No. 1

by John Victor Lacroix

Arthritis occasioned by indirect injury, such as characterizes joint inflammation from continuous concussion, is seen in horses that are worked at a rapid pace on city streets or other hard road surfaces. Such affections may be acute, as in some cases of spavin, but are usually inflammatory conditions that do not occasion serious disturbance when these affections become chronic. If the involvement persists with sufficient active inflammation, there may follow erosion of cartilage and incurable lameness. If extensive necrosis of cartilage takes place, the attendant pain will be sufficient to cause the animal to favor the diseased part and such immobilization enhances early ankylosis—nature's substitute for resolution in this disease.

Wounds invading the tissues adjacent to joints, when these wounds are of considerable extent, cause inflammation of such articulations by contiguous extension of inflammation. As long as an injury remains practically aseptic, or if infected and the septic process does not involve the joint proper by direct extension, no more serious disturbance than a simple synovitis will result. If, instead, a periarthritic inflammation is serious or destructive in character, the type of arthritis will be grave—even though due to an indirect cause.

Where a vulnerant body penetrates all structures and invades the interior of the joint capsule the result is that a more or less active disturbance is incited. The introduction of a sterile instrument into a joint cavity, under strict asepsis, where a perfect technic is executed, does not cause perceptible manifestation of the injury, if the opening so made is small—such as a suitable exploratory trocar makes. But a puncture made in a similar manner and with the same instrument without due regard to asepsis is likely to cause an infectious synovitis and arthritis usually follows.

A larger opening than is produced by means of an exploratory trochar may be made into a joint cavity, causing escape of synovia as it is secreted for days and even for weeks and no serious or permanent trouble is experienced in some cases. If the synovitis or arthritis remains non-infected and the wound, traumatic or surgical, is not too large, healing by granulation occurs, and the discharge of synovia ceases. However, if synovial discharge persists too long because of tardy closure of an open joint, there is great danger of infection gaining entrance into the synovial cavity, or in some instances, desiccation of endothelial cells of the articulation occurs, in areas, and the reactionary inflammation eventually results in ankylosis.

A small puncture which introduces into the synovial cavity infectious material of active virulence will cause an arthritis that is more serious, much more painful and more difficult to handle than is occasioned by a wound of moderate size, that affords ready escape of synovia even through the virulence of the infection be the same.

Synovia is a good culture medium and the environment is ideal for multiplication of bacteria; consequently, the grave disturbances which may attend the introduction of pathogenic organisms into a synovial cavity as the result of a puncture wound are not to be forgotten. The veterinarian is in no position to estimate the virulency of organisms so introduced; neither can he determine the exact degree of resistance possessed by the subject in any given case. Therefore, he is uncertain as to the best method of handling such cases where an injury has been recently inflicted and positive evidence of the existence of an infectious synovitis is not present. If one could determine in advance the degree of infection and injury that is to follow small penetrant wounds of joint capsules, it would then be possible to select certain cases and immediately drain away all synovia and fill the cavity by injection with suitable antiseptic solutions.

This offers a broad field for experimentation which will in time be productive of a radical change in the manner of treating such cases.

Metastatic arthritis is seen more frequently in colts or young animals than in mature horses and we here take the liberty of classifying with the arthritis of omphalophlebitis and strangles the so-called rheumatic variety.

A specific polyarthritis or synovitis which attends navel infection of foals is perhaps the most frequent form of arthritis that is to be considered metastatic. This condition is truly a disease of young animals and, while it is a specific arthritis, the cause is yet to be attributed to any definite pathogenic organism with certainty. This condition is well defined by Bollinger as quoted by Hoare,[1] when he calls it a purulent omphalophlebitis due to local infection of the umbilicus and umbilical vessels, by pyogenic organisms, causing a metastatic pyemia.